This invention relates to a belt splice and a method of splicing a belt. In the prior art, numerous belt splicing techniques and belt splices formed thereby are known. For example, early belts were made from leather which was spliced together through the use of glue and a splice interface angled with respect to the longitudinal axis of the belt at a small acute angle so as to increase the surface area of glue contact. Later, cotton fabric belts were made by calendering rubber into the fabric and stacking the fabric plies together to form a strong belt. In this technique, a stepping of the mating edges of the belt was used to enhance the connection. Both of these examples of prior art splicing methods and splices formed thereby may be catologued as bonding methods of splicing. Additionally, mechanical splicing methods have been used as well as combinations of mechanical and bonding methods of splicing.
In the mechanical catagory of splices, often, the interface area is fitted with an elongated hinge in an attempt to render the splice flexible in the direction transverse to the longitudinal direction thereof. This technique requires the introduction into the splice of the hinge pin which not only causes shock and strain in the belt when it passes over the conveyor pulleys but which hinge pin is also easily and rapidly worn by the inherent flexing which takes place at the hinge pin during its movement between flat and curved regions of the conveyor system. A further limitation of the hinge-type splice lies in the fact that the joint must be applied to the belt at precisely a right angle to the elongation of the belt since otherwise the belt would be distorted when forced to move over a curved surface such as a pulley.
A further mechanical splicing means comprises the embedding within the faces of the belt ends of a solid steel plate. Although this is an improvement in other designs due to the lack of metallic or other elements on the belt surfaces, this splicing device has limited application because it causes the belt to have a flat spot at the area of the splice even when the belt splice is going around a pulley, thereby causing extreme stress to be placed upon the spliced area.
Sometimes, the flat plate approach is augmented by bolts or rivets which extend completely through the belt and the plate on both sides of the splice. When these techniques are employed, the splice is optimized by grinding down portions of the metallic fasteners which arise above the belt surfaces. This grinding procedure, which is necessary to ensure avoidance of unfavorable interactions with the conveyor equipment, results in basic weakening of the fasteners. Furthermore, the inclusion of fasteners at the splice act to concentrate the belt pull forces at the fastener sites, thereby resulting in high levels of belt stress thereat. These high stress concentrations may be somewhat reduced through the utilization of a large number of fasteners, however, this adds time and expense to the splicing process.
Another type of splice consists of a stepped splice which is mostly used in belts having several layers bonded together. This type of splice is extremely time consuming and expensive to make because due to the high adhesion between belt layers, mechanical equipment must be used to pull the belt apart at the various layers. Very often, the rubber layers fail to strip off at exactly the bonded surfaces thereby leaving patches of rubber which must be ground away thereby damaging the fabrics contained between the layers. No way has yet been devised to accurately grind away these rubber patches without damaging the fabrics and thus the stepped method and step splice has severe limitations.
The following prior art is known to applicant:
U.S. Pat. Nos. 1,250,958 to Brooks discloses a belt fastener including a metal plate placed within split portions of the facing belt ends which plate is secured to the ends through the use of a plurality of rivets extending therethrough. The deficiencies of this solid metallic plate have been discussed hereinabove as have the deficiencies of metallic fasteners.
U.S. Pat. Nos. 1,421,036 and 1,428,917 both to Snyder are similar to Brooks as utilizing solid metal plates embedded within the belt and fastened thereto through the use of rivets. The main difference between the Snyder patents lies in the flat nature of the plate of Snyder '036 and the curved nature of the plate in Snyder '917.
U.S. Pat. No. 1,792,718 to Stoll discloses a belt splice utilizing a ribbon of metal or other material having a relatively high tensile stress inserted within slits in the belt ends and fastened thereto through the use of rivets. Thus, the limitations of Stoll are similar to those discussed with respect to the patents discussed hereinabove.
U.S. Pat. No. 3,076,736 to McHugh discloses a belt formed with tubular strength elements longitudinally therein which accept auxilliary splice elements along with adhesive or vulcanization to secure ends of the belting together. Since the McHugh belt requires the tubular strength elements, McHugh's splice is not usable with other types of belts. Furthermore, the tubular elements are completely different both structurally and functionally from the metallic fabric device of Applicant.
U.S. Pat. No. 3,224,566 to Elliot exemplifies the stepped splice discussed hereinabove and is believed different from the present invention as requiring a joining member of a non-metallic fabric while also requiring very difficult cuts in the belt ends so as to provide the stepped configuration thereof.
U.S. Pat. No. 4,376,668 to Ginter, Jr., et al. discloses a splice utilizing a pair of splice members made of a non-metallic fabric which are fastened within the belt ends through the use of nails disclosed as being made of, for example, rigid nylon or metal. This teaching is believed to be similar to the fastener teachings of Brooks, Snyder and Stoll as discussed hereinabove. Although the splice members of Ginter, Jr., et al. are flexible, the nail fasteners cause problems in concentration of forces as well as interference with conveyor components as described hereinabove. While the splice elements of Ginter, Jr., et al. are disclosed as being of a flexible nature, their strength is limited since they are not made of metal but rather are disclosed as being made of a material such as nylon fibers having a rubber-like or elastomeric material bonded to the surfaces thereof.